Brake-control mechanism



Nov. 9 1926.

V F. ATHIMON BRAKE CONTROL MECHANISM j Filed Feb. 12, 1926 Patented v.v 9, 1926.

UNITED STATES PATEN'I'IOFFIVCEQY FRANCIS ATHIMON, OF PARIS, FRANCE.

BRAKE-CONTROL MECHANISM.

Application filed February 12, 1926, Serial No. 87,925, and in France February 17, 1925.

The presentinvention is chiefly applicable to the control of brakes in which in order to obtain the equivalent of a servo-motor.

taining the preliminary or free stroke and a more moderate slope for the stroke corresponding to eflective braking, and secondly means to automatically compensate for the wear for instance the controlling device-re ferred to in my copending patent application Serial No. 17,055, filed March 20, 1925.

In a brake control device mounted on a vehicle the transmission rod and link gear may be subject to great elongations under certain severe shocks due for instance to unevenness of the road, and it is obvious that if great shocks occur at each braking operation, the awl or like means adapted to automatical y compensate for the wear will come into action even if there is no actual wear to be taken up, and such improper adjustments will unduly reduce the preliminary or free stroke. Furthermore, sincea part of the braking action itself takes place upon the rapid slope portion of the cam intended for the preliminary stroke, there will result an increased stress at this point.

In the arrangement according to my invention, I take advantage of this last'condition, and I effect the preliminary stroke by bearing not upon the cam itself but upon a lever having the same outline and mounted in an elastic manner. Said lever is held in its normal position under a tension which is suflicient to withstandwithout displacement-the efl'ort normally developed during the preliminary stroke, but not strong enough to withstand the additional efi'ort due to 'an improper or unnecessary adjustment. The displacement of the lever in this latter case is. utilized (through suitable means) 'to raise the adjusting pawl or likev means for the time necessary to prevent its action upon the adjusting ratchet wheel.

7 Further characteristics will appear from I the following description.

I In the appended drawings and by way of example:

Fig. 1 is a View of the device in the inoperative position, mounted upon a brake controlling arrangement, and

Fig. 2 is .a section on the line 2-2 of- Fig.

Fig. 3 shows-the said device-during the operation.

Fig. 4 isa section\on the line 44. of Fig;

A preferred embodiment of the present invention consists of the following elements:

Upon the controlling cam '1 which is secured on-or formed in one part with the pedal 2partly shown in the drawingsis mounted the lever 3 which is movable on the axle 4 and is caused to bear, by means of a spring 5 whose attaching point is adjustable, firstly against an abutment 6 of the cam 1, and secondly against the roller revoluble on the axle 11 mounted on the lever 9, through the fork which is formed by the said lever perpendicularly to the plane of Fig. l; at the interior of said fork is a portion of larger diameter 8 through which is inserted the brake controlling rod 12.

The lever 9 is movable on an axle '10 which is mounted upon the vehicle frame; said lever comprises an arm '13 (Fig. 2), perpendicular to its plane and upon which is mounted preferably by means of a screw .14

a pawl 15 formed in one vwith a ramp 17 and a tooth 18. Said awl is connected with the lever 9 by a sma spring 19' which serves to press the tooth of the pawl against 'one of the teeth of a ratchet wheel 20. A-

small spring 21 rivetted at the top of the pawl" allows a slight back.motion of said pawl without 'moving the wheel 20; the

point of the pawl acts inthis manner when the traction on the rod 12is considerably reduced, so that the points of the'teeth-.;of the wheel will'not be damaged durin the engagement. Adjacent the said whee is a nut 22 mounted on the controlling rod 12 and in contactthrough the extension part 23 with a cylindrica recess in the part 8 of the axle 11. A lever 24 is pivoted on anaxle 25 which is mounted on the lever 9.

abling it to bear on one side upon the ramp 17 and on the other side upon the lever 3,

either by means of the stud 26 mounted on .The said lever comprises three arms en- In the operative position (Fig. 1) the brake being well ad u Stedand the rod 12 being pressed by the reaction springs vof the cam being somewhat setback. .When the brakes are thrown on, the pedal 2 will be moved in the direction of the arrow.

Due to the spring 5, the part 28 of the lever 3 will resist (without movement) the tangential stress necessary, for makin the preliminary stroke. The lever 24 wlll not act upon the ramp 17 nor upon the pawl 15; the pivoting of the lever 9 and hence the motion of the ratchet wheel relatively to the pawl 15 being less than the pitch of a tooth of said ratchet wheel, there will be no pressure of the ratchet wheel upon the part 8.

Since the braking action is usually accompanied by aslight bending of the parts, it may be admitted that the braking Wlll commence immediately after the prellminary stroke, and will attain its maximum somewhat before the point 29 of the cam 1.

But if the preliminary stroke has been sufliciently increased by reason of the wear,

the cam 1 may act for braking purposes for instance as far as the point 29, The lever 9 is driven farther out, and hence the relative motion of the wheel 20 and the said pawl may be sutlicient to enable the latter to slip by one tooth upon the wheel, and u on returning to the inoperative position it will slightly press the wheel 20.

If by reason of shocks or jarring, the temporary elongations of the rod and link gear sistance of the spring 5.

ave already occasioned improper adjusting ellects resulting in an excessive pressure of the wheel 20, the braking stroke will occur sooner, the lever 3 will operate during the first part of this stroke, and the resulting tangential elfort will overcome the re- The lever 3 will then turn upon the axle 4; it will abut against the stud 27 of the lever 24 and will thus rotate the said lever; the latter slides upon the ramp 17 and thus enga es in the notch 18, rotating the pawl 15 ig. 4) which thus remains disenga ed durin the whole braking operation, so t at all a justment becomes impossible. Upon returning to the inoperative position, the

stud 26 of the lever 3 acts upon the corresponding arm of the lever24 and releases it as well as the pawl 15.

v The same efiect takes place at each braking operation, until the wear permits a re-' duction of the efiort upon the lever 3 on the point 28.

In view of'the preceding considerations, the pawl can proceed beyonda tooth of the wheel'only when in the maximum bra-king osition. In the event of a succession of ight braking operations, there might be produced a momentary displacement of the beginning irrespectively of any wear that might have.

of the braking operation, for,

no urred, the pawl could not attain the point iit'which'it passes over a tooth. I 5

To obviate this defect, the jumping point of the pawl is for instance brought to a pewhich are given solely by way of example,

and in particular the invention will not be modified it the arrangement of the cam l and the roller 7 is reversed, i. e. if the cam with its two inclined parts is mounted on the lever 9 and the roller is mounted at the I end of an arm secured to the pedal 2.

Having now described my invention, what I claim as new and desire to secure by Letters Patent is:

1. In a brake control comprising a control member, a rocking member, one of said members being provided with a cam outline with two ramps of different slopes respectively corresponding to the preliminary stroke and to the effective braking stroke, a transmissionrod and link attachment, adjusting means adapted to be actuated by said rocking member and to automatically compensate for the variations in length of the said transmission attachment, the combination of yielding means for operatively preventing any untimely operation of said adjusting means.

2. In a brake control comprisingv a control member, a rocking member, one of said members being provided with a cam outline with two ramps of different slopes respec tively correspondin to the preliminary stroke and to the e ective braking stroke; a transmission rod and link attachment, adjusting means adapted to be actuated by said rock-ing member and to automatically compensate for the variations in length of the said transmission attachment, the combination of a yieldingly mounted rockin lever adapted to oppose the eifort-due'to t e preliminary stroke and to oscillate under an abnormally great etfort due to an untimely operation of said adjusting means and means adapted to operatively transmit the displacements of said rocking lever to said adjusting means and to prevent any untimely operation nation of a yieldingly mounted rocking lever adapted to op ose the effort due to the preliminary stro e and to oscillate under an abnormally great'efi'ort due to an untimely operation of said adjusting means, a pin secured on said rocking lever, a three arm rocking lever, whereof one arm is adapted to operatively engage said pin a second arm .is adapted to abut against said first named .rocking lever and the third arm is adapted to operatively engage an extension provided on said pawl and to operatively prevent any untimely working of said pawl.

4. In a brake control comprising a control member, a rockingmember, one of said members being provided with a cam outline with two ramps of difierent slopes respectively corresponding to the preliminary stroke and to the eifective braking stroke, a transmission rod and link attachment, a pawl and ratchet wheel mechanism adapted to be actuated by said rocking member and to automatically compensate for the variations in length of the said transmission attachment, the combination of a rocking lever yieldingly mounted on one of said two first named members and adapted to oppose the effort due to the preliminary stroke and to oscillate under an abnormally great efiort'du'e to an untimely operation of said adjusting means a pin secured on said rocking lever, a roller, an adjustable yielding member adapted to cooperate with said rocking lever and to cause the latter to bear against said roller, a three arm rocking lever rotatably mounted on the other of said two first named members and whereof one arm is adapted to operatively engage said pin, a. secondarm is adapted to abut against said first named rocking lever and the third arm is adapted to operatively engage an extension provided on said pawl and to operatively prevent any untimely working of said pawl.

In testimony whereof I have signed my name'to this specification.

FRANCIS ATHIMON. 

